in my simulation some of the water is stuck on walls blender 2.82
Go to the Liquid menu. Check Fractional Obstacles, and drag that value all the way up to 1.

The reason this is happening is that the fluid simulator is actually based upon lots of 3D "cells". The cup, in a fluid simulation point of view, is basically a lot of obstacle cubes stacked together. The size of these cubes is determined by the fluid resolution. This causes a stair-stepping effect like the one you are seeing, where the liquid stands on a seemingly sloped surface.

By using the Fraction Obstacles feature, it is telling the fluid simulator to make the cell representation of an obstacle more like the original mesh bysmoothing it out.